I think the LHR-IOM slot was released back to Virgin from Jet Airways. The turn-time is more suitable for long-haul departures, at two hours. I don't know if VS will have a better use for it over the winter, or if another long-haul airline may lease it again. If VS can delay retirement of some outgoing aircraft they may be able to launch BOM themselves, BA have already added 4 additional weekly services.